Spiral wound membrane module for forward osmotic use

ABSTRACT

A spiral wound membrane module for forward osmotic use is disclosed. The membrane module may generally include a forward osmosis membrane in a spiral wound configuration. The module may include two inlets and two outlets, and may define first and second fluid flow paths. The inlets to each of the fluid flow paths may be generally isolated so as to prevent mixing. In some embodiments, the membrane module may include a distributer region and a collector region.

RELATED APPLICATIONS

This application claims the benefit of priority to U.S. ProvisionalPatent Application Ser. No. 61/070,087, filed Mar. 20, 2008; which ishereby incorporated by reference in its entirety.

FIELD OF THE TECHNOLOGY

One or more aspects relates generally to osmotic separation. Moreparticularly, one or more aspects relate to membrane modules for use inengineered osmosis, such as pressure retarded osmosis or any osmoticseparation of solutes and water from an aqueous solution by, forexample, forward osmosis, such as seawater desalination, brackish waterdesalination, wastewater purification and contaminated waterremediation.

BACKGROUND

Forward osmosis has been used for desalination. In general, a forwardosmosis desalination process involves a container having two chambersseparated by a semi-permeable membrane. One chamber contains seawater.The other chamber contains a concentrated solution that generates aconcentration gradient between the seawater and the concentratedsolution. This gradient draws water from the seawater across themembrane, which selectively permits water to pass but not salts, intothe concentrated solution. Gradually, the water entering theconcentrated solution dilutes the solution. The solutes are then removedfrom the dilute solution to generate potable water.

SUMMARY

Aspects relate generally to systems and methods for osmotic separation.

In accordance with one or more embodiments, a spiral wound forwardosmosis membrane module may comprise a spirally wound forward osmosismembrane defining a membrane pocket having an interior region and anexterior region, the spirally wound forward osmosis membrane havingfirst and second ends. The module may further comprise a distributerregion at the first end comprising a first inlet in fluid communicationwith the interior region of the membrane pocket and a second inlet influid communication with the exterior region of the membrane pocket. Themodule may still further comprise a collector region at the second endcomprising a first outlet in fluid communication with the interiorregion of the membrane pocket and a second outlet in fluid communicationwith the exterior region of the membrane pocket.

In some embodiments, the first inlet may be fluidly isolated from thesecond inlet. The first outlet may be fluidly isolated from the secondoutlet. The distributor region may comprise an end cap which may beconstructed and arranged to fluidly isolate the first and second inlets.In one embodiment, the end cap may comprise at least one tube having alumen fluidly connected to the interior region of the membrane pocketand an exterior region in fluid communication with the exterior regionof the membrane pocket. The first inlet may be fluidly connected to thelumen of the at least one tube. The second inlet may be in fluidcommunication with the exterior region of the at least one tube.

In some embodiments, at least a portion of one of the first and secondends of the spirally wound forward osmosis membrane may be potted. Inother embodiments, at least a portion of one of the first and secondends of the spirally wound forward osmosis membrane may be mounted in aplate. The module may further comprise at least one spacer positionedalong a fluid flow path defined by the interior region of the membranepocket from the first inlet to the first outlet. The module may alsocomprise at least one spacer positioned along a fluid flow path definedby the exterior region of the membrane pocket from the second inlet tothe second outlet. In some embodiments, a thickness of the at least onespacer may vary along a longitudinal axis of the membrane module. Atleast one embodiment the module may include a center support inmechanical cooperation with the spirally wound forward osmosis membrane.In some embodiments, the spirally wound forward osmosis membrane isasymmetric. The exterior region of the membrane pocket may be defined bya rejecting layer of the spirally wound forward osmosis membrane. Insome embodiments, the module may be integrated in a pressure retardedosmosis system.

In accordance with one or more embodiments, a water treatment system maycomprise a spiral wound forward osmosis membrane module comprising aspirally wound forward osmosis membrane constructed and arranged todefine isolated and substantially parallel first and second fluid flowpaths along a longitudinal axis of the module, a first inlet and a firstoutlet fluidly connected to the first fluid flow path, and a secondinlet and a second outlet fluidly connected to the second fluid flowpath. The water treatment system may further comprise a source of afirst solution fluidly connected to the first inlet, and a source of asecond solution fluidly connected to the second inlet.

In some embodiments, the first and second inlets may be positioned at afirst end of the spirally wound forward osmosis membrane. The source ofthe first solution may be a source of a saline solution. In someembodiments, the saline solution comprises seawater. The source of thesecond solution may comprise a source of a draw solution. In at leastone embodiment, the draw solution may comprise ammonia and carbondioxide in a molar ratio of greater than about 1 to 1.

In some embodiments, the water treatment system may further comprise asecond forward osmosis spiral wound membrane module. The system may alsoinclude a control system configured to control at least one of a flowrate of the first solution at the first inlet and a flow rate of thesecond solution at the second inlet. In at least one embodiment, thesystem may include a separation system fluidly connected to one of thefirst and second outlets. In some embodiments, an outlet of theseparation system may be fluidly connected to one of the first andsecond inlets. In at least one embodiment, the system is a pressureretarded osmosis system further comprising a turbine fluidly connecteddownstream of one of the first and second outlets.

In accordance with one or more embodiments, a method of facilitating adesalination process may comprise providing a spiral wound forwardosmosis membrane module comprising a spirally wound forward osmosismembrane defining a membrane pocket having an interior region and anexterior region, the spirally wound forward osmosis membrane havingfirst and second ends, a distributer region at the first end comprisinga first inlet in fluid communication with the interior region of themembrane pocket and a second inlet in fluid communication with theexterior region of the membrane pocket, and a collector region at thesecond end comprising a first outlet in fluid communication with theinterior region of the membrane pocket and a second outlet in fluidcommunication with the exterior region of the membrane pocket. Themethod of facilitation may further include fluidly connecting a sourceof a draw solution to the first inlet and fluidly connecting a source ofa brine solution to the second inlet.

In some embodiments, fluidly connecting a source of a draw solution tothe first inlet may comprise fluidly connecting a source of a drawsolution comprising ammonia and carbon dioxide in a molar ratio ofgreater than about 1 to 1. The method may further comprise fluidlyconnecting the first outlet to a distillation column. In at least oneembodiment, the method may further comprise fluidly connecting an outletof the distillation column to the first inlet. The spiral wound forwardosmosis membrane or the provided module may be constructed and arrangedto define isolated and substantially parallel first and second fluidflow paths along a longitudinal axis of the module. In at least oneembodiment, the method is a pressure retarded osmosis process furthercomprising fluidly connecting the collector region of the membranemodule to a turbine.

Still other aspects, embodiments, and advantages of these exemplaryaspects and embodiments, are discussed in detail below. Moreover, it isto be understood that both the foregoing information and the followingdetailed description are merely illustrative examples of various aspectsand embodiments, and are intended to provide an overview or frameworkfor understanding the nature and character of the claimed aspects andembodiments. The accompanying drawings are included to provideillustration and a further understanding of the various aspects andembodiments, and are incorporated in and constitute a part of thisspecification. The drawings, together with the remainder of thespecification, serve to explain principles and operations of thedescribed and claimed aspects and embodiments.

BRIEF DESCRIPTION OF THE FIGURES

Various aspects of at least one embodiment are presented in theaccompanying figures. The figures are provided for the purposes ofillustration and explanation and are not intended as a definition of thelimits of the invention. In the figures:

FIG. 1 presents a schematic drawing of a spiral wound forward osmosismembrane module in accordance with one or more embodiments;

FIG. 2 presents a schematic drawing of a spiral wound forward osmosismembrane module component with end caps in accordance with one or moreembodiments;

FIG. 3 presents a schematic drawing of an end cap in accordance with oneor more embodiments;

FIG. 4 presents a schematic side-view of an end cap in accordance withone or more embodiments;

FIG. 5 presents a schematic cross-sectional view of an end cap inaccordance with one or more embodiments;

FIG. 6 presents a schematic drawing of an end portion of a spiral woundforward osmosis membrane module in accordance with one or moreembodiments; and

FIG. 7 presents a schematic drawing of a flow pattern through a spiralwound forward osmosis membrane module component in accordance with oneor more embodiments.

DETAILED DESCRIPTION

In accordance with one or more embodiments, an osmotic method forextracting water from an aqueous solution may generally involve exposingthe aqueous solution to a first surface of a forward osmosis membrane. Asecond solution, or draw solution, with an increased concentrationrelative to that of the aqueous solution may be exposed to a secondopposed surface of the forward osmosis membrane. Water may then be drawnfrom the aqueous solution through the forward osmosis membrane and intothe second solution generating a water-enriched solution via forwardosmosis which utilizes fluid transfer properties involving movement froma less concentrated solution to a more concentrated solution. Thewater-enriched solution, also referred to as a dilute draw solution, maybe collected at a first outlet and undergo a further separation processto produce purified water. A second product stream, i.e. a depleted orconcentrated aqueous process solution, may be collected at a secondoutlet for discharge or further treatment.

Hydraulic pressure may generally promote transport of the first andsecond solutions through a membrane module along a longitudinal axis oftheir respective channels, while osmotic pressure may generally promotetransport of water across a forward osmosis membrane in the module fromthe feed to the draw solution. Alternately, hydraulic pressure may beexerted on the feed solution to assist the flow of water from the feedto draw solutions, or hydraulic pressure may be placed on the drawsolution to allow the production of power from the expansion of thevolume of the draw solution due to membrane flux of water from the feedsolution driven by the osmotic pressure difference between the twosolutions (PRO). Generally, flow channels within the module are designedto minimize the hydraulic pressure necessary to cause flow through thesechannels (crossflow), but this is often at odds with the desire tocreate turbulence in the flow channels, beneficial for efficientgeneration of osmotic pressure difference between the two solutions,which has a tendency to increase resistance to flow. Higher osmoticpressure differences may generally increase transmembrane flux, but mayalso have a tendency to increase the amount of heat required to separatethe draw solutes from the dilute draw solution for production of adilute water product and a reconcentrated draw solution.

In accordance with one or more embodiments, a forward osmosis membranemodule may include one or more forward osmosis membranes. The forwardosmosis membranes may generally be semi-permeable, for example, allowingthe passage of water, but excluding dissolved solutes therein, such assodium chloride, ammonium carbonate, ammonium bicarbonate, and ammoniumcarbamate. Many types of semi-permeable membranes are suitable for thispurpose provided that they are capable of allowing the passage of water(i.e., the solvent) while blocking the passage of the solutes and notreacting with the solutes in the solution. The membrane can have avariety of configurations including thin films, hollow fiber membranes,spiral wound membranes, monofilaments and disk tubes. There are numerouswell-known, commercially available semi-permeable membranes that arecharacterized by having pores small enough to allow water to pass whilescreening out solute molecules such as sodium chloride and their ionicmolecular species such as chloride. Such semi-permeable membranes can bemade of organic or inorganic materials. In some embodiments, membranesmade of materials such as cellulose acetate, cellulose nitrate,polysulfone, polyvinylidene fluoride, polyamide and acrylonitrileco-polymers may be used. Other membranes may be mineral membranes orceramic membranes made of materials such as ZrO₂ and TiO₂.

Preferably, the material selected for use as the semi-permeable membraneshould generally be able to withstand various process conditions towhich the membrane may be subjected. For example, it may be desirablethat the membrane be able to withstand elevated temperatures, such asthose associated with sterilization or other high temperature processes.In some embodiments, a forward osmosis membrane module may be operatedat a temperature in the range of about 0 degrees Celsius to about 100degrees Celsius. In some non-limiting embodiments, process temperaturesmay range from about 40 degrees Celsius to about 50 degrees Celsius.Likewise, it may be desirable for the membrane to be able to maintainintegrity under various pH conditions. For example, one or moresolutions in the membrane environment, such as the draw solution, may bemore or less acidic or basic. In some non-limiting embodiments, aforward osmosis membrane module may be operated at a pH level of betweenabout 2 and about 11. In certain non-limiting embodiments, the pH levelmay be about 7 to about 10. The membranes used need not be made out ofone of these materials and they can be composites of various materials.In at least one embodiment, the membrane may be an asymmetric membrane,such as with an active layer on a first surface, and a supporting layeron a second surface. In some embodiments, an active layer may generallybe a rejecting layer. For example, a rejecting layer may block passageof salts in some non-limiting embodiments. In some embodiments, asupporting layer, such as a backing layer, may generally be inactive.

In accordance with one or more embodiments, the at least one forwardosmosis membrane of the membrane module may be spirally wound. A spiralwound configuration may be generally efficient in terms of facilitatingforward osmosis within the module. The spiral wound configuration may bedesirable in terms of containment of large amounts of surface area perunit of volume. The spiral wound configuration may also be desirable interms of surface area contact along a fluid flow path with respect toresidence time of a process stream within the forward osmosis membranemodule. The membrane module may also be beneficially designed so as toreduce frictional resistance to fluid crossflow through the fluid flowchannels, and to reduce dead spaces and poor mass transport, whileencouraging turbulent flow. In at least one embodiment, both draw andfeed solutions may travel along the longitudinal axis of the membranemodule with minimal resistance or diversion of flow. A spirally woundforward osmosis membrane module may be of any desired dimensions.

In accordance with one or more embodiments, at least one forward osmosismembrane may be positioned within a housing or casing. The housing maygenerally be sized and shaped to accommodate the membranes positionedtherein. For example, the housing may be substantially cylindrical ifhousing spirally wound forward osmosis membranes. The housing of themodule may contain inlets to provide feed and draw solutions to themodule as well as outlets for withdrawal of product streams from themodule. In some embodiments, the housing may provide at least onereservoir or chamber for holding or storing a fluid to be introduced toor withdrawn from the module. In at least one embodiment, the housingmay be insulated. In some non-limiting embodiments, a module assemblymay be sealed inside a tubular housing such that seawater is passed intoa space in-between epoxy blocks and the main sheet winding. Drawsolution may pass through the interior of flat tubes leading thesolution across a supporting layer side within the sheet winding.

In accordance with one or more embodiments, a forward osmosis membranemodule may generally be constructed and arranged so as to bring a firstsolution and a second solution into contact with first and second sidesof a semi-permeable membrane, respectively. Although the first andsecond solutions can remain stagnant, it is preferred that both thefirst and second solutions are introduced by cross flow, i.e., flowsparallel to the surface of the semi-permeable membrane. This maygenerally increase membrane surface area contact along one or more fluidflow paths, thereby increasing the efficiency of the forward osmosis. Insome embodiments, the first and second solutions may flow in the samedirection. In other embodiments, the first and second solutions may flowin opposite directions. In at least some embodiments, similar fluiddynamics may exist on both sides of a membrane surface. This may beachieved by strategic integration of the one or more forward osmosismembranes in the module or housing.

In accordance with one or more embodiments, a forward osmosis membranemodule may generally be constructed and arranged to provide a firstfluid flow path and a second fluid flow path. The flow paths maygenerally run along a longitudinal axis of the module, such as from afirst end to a second end. The first and second fluid flow paths may beseparated by the forward osmosis membrane. A first solution may travelalong the first fluid flow path and a second solution may travel alongthe second fluid flow path through the module. In the case of anasymmetric forward osmosis membrane, an active layer of the membrane maybe associated with a first fluid flow path, and a supporting layer maybe associated with a second fluid flow path. In at least one embodiment,aqueous water to be treated, such as seawater, may be in contact withthe active layer of the forward osmosis membrane while the draw solutionmay be in contact with the supporting layer. In other embodiments, theopposite may apply. In some embodiments, the first and second fluid flowpaths may be generally or substantially parallel to one another along alongitudinal axis of the membrane module. In at least one embodiment,the first and second fluid flow paths may be substantially isolated fromone another so as to generally prevent mixing therebetween, thoughtransmembrane osmotic passage of water from the first solution to thesecond solution within the module is desired to effect separation andpurification of the solvent as described above.

In accordance with one or more embodiments, the first solution may beany aqueous solution or solvent containing one or more solutes for whichseparation, purification or other treatment is desired. In someembodiments, the first solution may be non-potable water such asseawater, salt water, brackish water, gray water, and some industrialwater. A process stream to be treated may include salts and other ionicspecies such as chloride, sulfate, bromide, silicate, iodide, phosphate,sodium, magnesium, calcium, potassium, nitrate, arsenic, lithium, boron,strontium, molybdenum, manganese, aluminum, cadmium, chromium, cobalt,copper, iron, lead, nickel, selenium, silver and zinc. In some examples,the first solution may be brine, such as salt water or seawater,wastewater or other contaminated water. The first solution may bedelivered to a forward osmosis membrane treatment system from anupstream unit operation such as industrial facility, or any other sourcesuch as the ocean. The second solution may be a draw solution containinga higher concentration of solute relative to the first solution. A widevariety of draw solutions may be used. For example, the draw solutionmay comprise a thermolytic salt solution. In some embodiments, anammonia and carbon dioxide draw solution may be used, such as thosedisclosed in U.S. Patent Application Publication Number 2005/0145568 toMcGinnis which is hereby incorporated herein by reference in itsentirety for all purposes. In one embodiment, the second solution may bea concentrated solution of ammonia and carbon dioxide. In at least oneembodiment, the draw solution may comprise ammonia and carbon dioxide ina molar ratio of greater than about 1 to 1.

The draw solution generally has a concentration greater than that of thefeed solution. This may be achieved using solutes that are solubleenough to produce a solution that has a higher concentration than thefeed solution. Preferably, the solute within the second solution shouldbe easily removable from the second solution through a separationprocess, form at least one species that is more readily dissolved in thesolvent of the second solution, i.e., the soluble species, and onespecies that is not readily dissolved within the solvent, i.e., theless-soluble species, and posses no health risk if trace amounts of thespecies of solute remain in the resulting solvent. The existence of thesoluble and less-soluble species of solutes allows for the solutions tobe adjusted or manipulated as needed. Typically, the soluble andless-soluble solute species reach a point in solution in which, underthe particular condition temperature, pressure, pH, etc., neitherspecies of solute is either increasing or decreasing with respect to theother, i.e., the ratio of the soluble to insoluble species of solute isstatic. This is referred to as equilibrium. Given the particularconditions of the solution, the species of solute need not be present ina one to one ratio at equilibrium. Through the addition of a chemical,referred to as a reagent, the balance between the species of solutes canbe shifted. Using a first reagent, the equilibrium of the solution canbe shifted to increase the amount of the soluble species of solute.Likewise, using a second reagent, the equilibrium of the solution may beshifted to increase the amount of the less-soluble solute species. Afterthe addition of the reagents, the ratio of species of solutes maystabilize at a new level which is favored by the conditions of thesolution. By manipulating the equilibrium in favor of the solublespecies of solute, a second solution with a concentration nearsaturation can be achieved, a state in which the solutions solventcannot dissolve anymore of the solute.

Preferred solutes for the second (draw) solution may be ammonia andcarbon dioxide gases and their products, ammonium carbonate, ammoniumbicarbonate, and ammonium carbamate. Ammonia and carbon dioxide, whendissolved in water at a ratio of about 1, form a solution comprisedprimarily of ammonium bicarbonate and to a lesser extent the relatedproducts ammonium carbonate and ammonium carbamate. The equilibrium inthis solution favors the less-soluble species of solute, ammoniumbicarbonate, over the soluble species of solute, ammonium carbamate andto a lesser extent ammonium carbonate. Buffering the solution comprisedprimarily of ammonium bicarbonate with an excess of ammonia gas so thatthe ratio of ammonia to carbon dioxide increases to about 1.75 to about2.0 will shift the equilibrium of the solution towards the solublespecies of the solute, ammonium carbamate. The ammonia gas is moresoluble in water and is preferentially adsorbed by the solution. Becauseammonium carbamate is more readily adsorbed by the solvent of the secondsolution, its concentration can be increased to the point where thesolvent cannot adsorb anymore of the solute, i.e. saturation. In somenon-limiting embodiments, the concentration of solutes within thissecond solution achieved by this manipulation is greater than about 2molal, more than about 6 molal, or about 6 to about 12 molal.

Ammonia gas may be a preferred first reagent for ammonium carbamatesince it is one of the chemical elements that results when the soluteammonium carbamate is decomposed, otherwise referred to as a constituentelement. In general, it is preferred that the reagent for the solvent bea constituent element of the solute since any excess reagent can easilybe removed from the solution when the solvent is removed, and, in apreferred embodiment the constituent element can be recycled as thefirst reagent. However, other reagents that can manipulate theequilibrium of the solute species in solution are contemplated so longas the reagent is easily removed from the solution and the reagentposses no health risk if trace elements of the reagent remain within thefinal solvent.

In accordance with one or more embodiments, a forward osmosis membranemodule may generally include first and second inlets. The first andsecond inlets may be associated with sources of first and secondsolutions. In some embodiments, a source of a first solution may be afirst solution reservoir and a source of a second solution may be asecond solution reservoir. A first inlet may be fluidly connected to asource of an aqueous solution to be treated, and a second inlet may befluidly connected to a source of a draw solution. The first and secondinlets may also be associated with the first and second fluid flowpaths, respectively, so as to facilitate delivery of first and secondsolutions to the membrane module for forward osmosis. In someembodiments, the first inlet may be in fluid communication with thefirst fluid flow path, and the second inlet may be in fluidcommunication with the second fluid flow path. The first and secondinlets may be fluidly isolated from one another. In at least oneembodiment, the first and second inlets are positioned at one end, i.e.a first or second end, of the forward osmosis membrane module. In otherembodiments, the first and second inlets may be positioned at oppositeends of the forward osmosis membrane module.

In accordance with one or more embodiments, a forward osmosis membranemodule may generally include first and second outlets. The first andsecond outlets may be associated with the first and second fluid flowpaths, respectively, so as to facilitate removal of one or more productstreams from the forward osmosis membrane module. A first outlet maycollect a dilute draw solution and a second outlet may collect adepleted or concentrated aqueous process stream. In some embodiments,the first outlet may be in fluid communication with the first fluid flowpath, and the second outlet may be in fluid communication with thesecond fluid flow path. The first and second outlets may be fluidlyisolated from one another. In at least one embodiment, the first andsecond outlets are positioned at one end of the forward osmosis membranemodule. In other embodiments, the first and second outlets may bepositioned at opposite ends of the forward osmosis membrane module.

In some embodiments, first and second inlets may generally be positionedat a first end of the forward osmosis membrane module while first andsecond outlets may generally be positioned at a second end of theforward osmosis membrane module. In some such embodiments, a distributorregion may generally provide the first and second inlets, and acollector region may generally provide the first and second outlets. Thedistributor region may be positioned at a first end of the membranemodule and the collector region may be positioned at a second end of themembrane module.

In accordance with one or more embodiments, the forward osmosis membraneof the module may be constructed and arranged to define a membranecompartment. A membrane compartment may generally define at least apartially enclosed space. Thus, a membrane compartment may have aninterior region and an exterior region. One or more sides of a membranecompartment may be sealed. In some embodiments, a membrane compartmentmay generally be referred to as a membrane pocket, having an interiorregion and an exterior region. A first fluid flow path may be associatedwith the interior region of the membrane pocket and a second fluid flowpath may be associated with the exterior region of the membrane pocket.The membrane pocket may generally facilitate isolation of the first andsecond fluid flow paths to prevent mixing, apart from desired osmotictransmembrane transport for separation. In embodiments involving anasymmetric membrane, a first layer of the membrane may provide a surfaceof the interior region of the compartment while a second layer of themembrane may provide a surface of the exterior region of thecompartment. In some embodiments, a rejecting layer may be associatedwith the exterior region of the membrane pocket and a supporting layermay be associated with the interior region of the membrane pocket.

In accordance with one or more embodiments, a forward osmosis membranemodule may include a plurality of forward osmosis membranes. A modulemay include a plurality of spirally wound forward osmosis membranes. Inembodiments wherein the membranes are constructed and arranged toprovide or define a membrane compartment or pocket, the module maycomprise a plurality of such compartments, each having an interiorregion and an exterior region. A membrane module may therefore comprisea plurality of first fluid pathways and a plurality of second fluidpathways. In some embodiments, the first fluid flow pathways may beassociated with interior regions of membrane pockets, while second fluidflow pathways may be associated with exterior regions of membranepockets, or spaces between adjacent membranes of the module. A firstsolution may flow along each of the first fluid pathways, and a secondsolution may flow along each of the second fluid pathways. Thus, amodule may be scaled-up by increasing the number of forward osmosismembranes, such as spirally wound forward osmosis membranes, present inthe module.

In accordance with one or more embodiments, a forward osmosis membranemodule may include one or more features to facilitate introduction offirst and second solutions to the membrane module while preventingmixing therebetween. Likewise, a forward osmosis membrane module mayinclude one or more features to facilitate withdrawal or collection offirst and second solutions from the membrane module while preventingmixing therebetween. In some embodiments, an end cap may be positionedat each end of a spiral wound membrane module. In at least oneembodiment, end caps may be positioned at each end of a spirally woundmembrane. In modules having a plurality of spirally wound membranes,each of the spirally wound membranes may have an end cap positioned ateach end. The end cap may include at least one inlet and/or outlet influid communication with one or more fluid flow paths within the module.The end cap may be constructed and arranged so as to facilitateisolation of one or more fluid flow paths within the module. The end capmay be constructed and arranged so as to isolate one or more fluidinlets and/or fluid outlets.

In some embodiments, an end cap may comprise a first inlet in fluidcommunication with a first fluid flow path and a second inlet in fluidcommunication with a second fluid flow path. In one embodiment, an endcap may comprise a first inlet in fluid communication with an interiorregion of a membrane compartment. The end cap may comprise a secondinlet in fluid communication with an exterior region of the membranecompartment.

In some embodiments, an end cap may comprise a first outlet in fluidcommunication with a first fluid flow path and a second outlet in fluidcommunication with a second fluid flow path. In one embodiment, an endcap may comprise a first outlet in fluid communication with an interiorregion of a membrane compartment. The end cap may also include a secondoutlet in fluid communication with an exterior region of the membranecompartment.

In other embodiments, a first end cap may include a first inlet in fluidcommunication with a first fluid flow path and a first outlet in fluidcommunication with a second fluid flow path. A second end cap mayinclude a second inlet in fluid communication with the second fluid flowpath and a second outlet in fluid communication with the first fluidflow path. The first end cap may be positioned at a first end of aspiral wound membrane and the second end cap may be positioned at asecond end of the spiral wound membrane. The first fluid flow path maybe along an interior region of a membrane pocket and the second fluidflow path may be along an exterior region of the membrane pocket.

In accordance with one or more embodiments, an end cap may comprise oneor more ports in fluid communication with one or more fluid flow pathsof the membrane module. The ports of the end cap may generallyfacilitate isolation of solutions introduced to or withdrawn from thespiral wound forward osmosis membrane module at the end cap. The portsmay have any structure capable of generally preventing mixing of varioussolutions introduced and/or withdrawn at an end cap. A port may beconstructed and arranged to isolate various solutions introduced and/orwithdrawn at an end cap. A port may comprise a first region in fluidcommunication with a first fluid flow path and a second region in fluidcommunication with a second fluid flow path. The first and secondregions may be arranged so as to prevent mixing between solutionsintroduced and/or withdrawn therefrom. The ports may generally be sizedand spaced so as to facilitate fluid flow through the membrane module,such as to achieve a desired flux. This flux is generally achieved byencouraging turbulent flow in a relatively straight flow path from oneend of the membrane module to the other, with minimum deviation of flowpath and minimum resistance to flow arising from the special dimensionsof the flow path.

In some embodiments, the ports may comprise tubes each having a lumenregion and an exterior region. In at least one embodiment the tubes maybe substantially flat tubes. Other embodiments envision oval or circulartube openings, and spaces between tubes taking rectangular, oval,triangular, or corrugated shapes, for example. One or more lumens may befluidly connected to a first fluid flow path, such as an interior regionof a membrane pocket, and an exterior region of the tubes may be influid communication with a second fluid flow path, such as an exteriorregion of the membrane pocket. The lumens may be fluidly connected to afirst inlet of the membrane module to facilitate introduction of a firstsolution to a first flow path while the exterior region of the tubes maybe fluidly connected to a second inlet of the membrane module tofacilitate introduction of a second solution to a second fluid flowpath. The lumens of another end cap may be fluidly connected to a firstoutlet of the membrane module to facilitate withdrawal of a firstsolution from a first flow path while the exterior region of the tubesmay be fluidly connected to a second outlet of the membrane module tofacilitate withdrawal of a second solution from a second fluid flowpath. In embodiments where an end cap comprises an inlet and an outlet,the lumens may be fluidly connected to a first inlet of the membranemodule to deliver a first solution to a first fluid flow path while theexterior region of the tubes may be fluidly connected to a first outletof the membrane module to withdraw a second solution from a second fluidflow path. Various other configurations apart from these exampleconfigurations are possible.

In accordance with one or more embodiments, a membrane module mayinclude one or more features to ensure isolation of fluid flow pathswithin the module but for desired transmembrane transport forseparation. The end caps described above may be one such feature. Otherfeatures may be implemented alone or in conjunction with the end caps.In some embodiments, at least a portion of one or more ends of a spiralwound forward osmosis membrane may be mounted with a plate or othermechanical or structural approach capable of preventing mixing betweenvarious solutions supplied or withdrawn from the module. In otherembodiments at least a portion of one or more ends of a spiral woundforward osmosis membrane may be potted to facilitate isolation of fluidflow paths. Various membrane potting techniques and materials arewell-known, and generally involve use of curable resin materials. Insome embodiments, potting may generally prevent a fluid entering orexiting a first fluid flow path from also entering or exiting a secondfluid flow path, and vice versa. For example, potting may prevent afirst fluid flowing into lumens of end cap tubes from also flowing inbetween the tubes. Likewise, potting may generally prevent a secondfluid flowing between end cap tubes from also flowing into lumens of theend cap tubes. In some non-limiting embodiments, this may be achievedwith any epoxy-like substance that is liquid and then solidifies. Somepotting materials are characterized as being generally rigid whileothers are more flexible. Each property has associated benefits and, insome embodiments, it may be desirable to use a combination of resinmaterials for potting. In embodiments where an end cap and/or plate orother mechanical or structural device is used, potting may offersupplemental protection against undesirable mixing at fluid inletsand/or outlets of a spirally wound forward osmosis membrane module.

In accordance with one or more embodiments, a forward osmosis membranemodule may generally be constructed and arranged to promote uniform fluxthrough the membrane module, such as along a longitudinal axis of themodule. A uniform flux may generally promote efficient use of availablemembrane surface area. Design considerations which may promote uniformflux include optimization of parameters such as, for example, flow rate,stream turbulence, balancing of the concentrations and volumes of thefeed and draw solutions, flow channel height, patterning on the membranesurface, flow distributors or supplementary flow distributers at eitherend of the membrane module to ensure even flow throughout the channelsat any point on the radial axis of the module, and the diameter andlength of the membrane module.

In accordance with one or more embodiments, a support structure may beassociated with the spirally wound membrane module. For example, a rodor shaft may support a spirally wound membrane. In some embodiments, oneor more forward osmosis membranes may be wrapped around a supportstructure. In certain embodiments, one or more forward osmosis membranepockets, such as a plurality, may be spiraled around a supportstructure. The one or more membranes may be connected to the supportstructure. In other embodiments, they may be unattached. In someembodiments, the module does not include a permeate tube, such as acentral permeate tube, for introduction or collection of one or morefluid streams. Thus, in at least one embodiment, the support structureis not a permeate tube.

In accordance with one or more embodiments, one or more spacers may bepositioned along one or more fluid flow paths. Spacers may generallyfacilitate promotion of uniform flux along fluid flow paths, may directfluid flow along flow paths, and may promote any desirable turbulencewithin the module. One or more spacers may be positioned along a firstfluid flow path and/or a second fluid flow path. In some embodiments,spacers may be positioned along a membrane pocket and/or along anexterior region of a membrane pocket. In at least some embodiments,spacers may be positioned between adjacent membranes of a membranemodule. Spacers may be used to strategically adjust one or moreparameters associated with a fluid flow path. For example, thedimensions, such as thickness, width or height of spacers may beselected so as to result in a desired height, volume, flux or otherparameter of a fluid flow path. It may be desirable to vary one or moreparameters of a fluid flow path along a longitudinal axis of a fluidflow path. In at least one embodiment, the thickness of spacers along alongitudinal axis of the membrane module may be varied to achieve adesired profile. For example, it may be desirable to taper one or morefluid flow paths along a longitudinal axis of a module.

In at least one embodiment, a spirally wound forward osmosis membranemodule does not include glue lines or is substantially free of gluelines. Use of glue lines is commonly known to generally facilitatedirection of fluid flow within a membrane module. In some embodiments, aforward osmosis membrane, such as one folded or otherwise constructedand arranged to form a compartment or pocket, does not include a glueline along a fluid flow path, such as to direct fluid flow. For example,some embodiments may not include a glue line associated with an interiorregion of a membrane pocket. One or more such membranes without gluelines may be spirally wound within a forward osmosis membrane module inaccordance with one or more embodiments. In some embodiments, glue oradhesive may still be used along the edges of a membrane pocket so as toseal the pocket, secure end caps and/or to connect the membrane to asupport structure.

A spirally wound membrane module in accordance with one or moreembodiments may be used in pressure retarded osmosis. Pressure retardedosmosis may generally relate to deriving osmotic power or salinitygradient energy from a salt concentration difference between twosolutions, such as a concentrated draw solution and a dilute workingfluid. In some examples, seawater may be a first solution and freshwater or nearly deionized water may be a second solution. In someembodiments, one or more spirally wound forward osmosis membrane modulesmay be enclosed in a pressure vessel to facilitate pressure retardedosmosis. One or more design aspects of the forward osmosis membranemodule, such as one or more characteristics or parameters pertaining tothe membranes, end caps, spacers or flow paths, may be modified forpressure retarded osmotic use. Within pressure retarded osmosis, a drawsolution may be introduced into a pressure chamber on a first side of amembrane, such as along a first fluid flow path of a spirally woundmembrane module. In some embodiments, at least a portion of the drawsolution may be pressurized based on an osmotic pressure differencebetween the draw solution and a dilute working fluid. The dilute workingfluid may be introduced on a second side of the membrane, such as alonga second fluid flow path of the spirally wound membrane module. Thedilute working fluid may generally move across the membrane via osmosis,thus increasing the volume on the pressurized draw solution side of themembrane. As the pressure is compensated, a turbine may be spun togenerate electricity. A resulting dilute draw solution may then beprocessed, such as separated, for reuse. In some embodiments, alower-temperature heat source, such as industrial waste heat may be usedin or facilitate a pressure retarded osmosis system or process.

In one non-limiting embodiment, a pressure retarded osmosis systemincorporating one or more spirally wound membrane modules may be anosmotic heat engine, such as that described in WIPO Publication No.WO2008/060435 to McGinnis et al. which is hereby incorporated herein byreference in its entirety for all purposes. An osmotic heat engine mayconvert thermal energy into mechanical work using a semi-permeablemembrane to convert osmotic pressure into electrical power. Aconcentrated ammonia-carbon dioxide draw solution may create highosmotic pressures which generate water flux through a semi-permeablemembrane against a hydraulic pressure gradient. Depressurization of theincreased draw solution volume in a turbine may produce electricalpower. The process may be maintained in steady state operation throughthe separation of diluted draw solution into a re-concentrated drawsolution and deionized water working fluid, both fore reuse in theosmotic heat engine.

In some embodiments, a forward osmosis module may be operated atpressures up to about 2000 psi. Some non-limiting forward osmosisembodiments may involve pressures between about 20 psi to about 50 psi.In operation, non-limiting example conditions for a forward osmosismodule may include about a 5 molar draw solution with no hydraulicpressure exerted on it other than the about 20 psi to about 40 psineeded to carry out crossflow through the draw solution flow channel,which is diluted to a concentration of approximately about 1.5 molar bythe transmembrane flux of water from the feed solution through thesemipermeable membrane. The feed solution in this case would for examplebe a seawater feed (approximately about 0.5 molar) which is notpressurized hydraulically other than to about 20 psi to about 40 psi toinduce its crossflow through the feed flow channel.

In some embodiments, a pressure retarded osmosis module may be operatedat pressures up to about 2000 psi. Some non-limiting pressure retardedosmosis embodiments may involve pressures between about 1000 psi andabout 2000 psi. In operation, non-limiting example conditions for apressure retarded osmosis module may include a draw solutionconcentration of about 5 molar becoming diluted to about 3 molar, undera hydraulic pressure of approximately about 100 atm. The feed solutionin this case would for example be a deionized water working fluid underonly the hydraulic pressure (about 20 psi to about 40 psi) needed toinduce its flow through the feed flow channel.

FIG. 1 presents a spiral wound forward osmosis membrane module 100 inaccordance with one or more non-limiting embodiments. Module 100includes a plurality of spirally wound forward osmosis membranes 110.Each end of the module 100 includes a chamber 120, 130. Chamber 120includes inlets 124, 126 while chamber 130 includes outlets 134,136.Each end of the membranes 110 is potted in pots 140.

Module 100 may be sized with any desired dimensions. For example, sizingmay be based on various factors including flow rate requirements andavailable footprint space. Modules may generally be scaled up or down toaccommodate specifications of a particular application. In somenon-limiting embodiments, the physical dimensions of module 100 may bebetween about 0.5 meters and about 2 meters in length. In one specificembodiment, module 100 may be about 1 meter in length. In somenon-limiting embodiments, module 100 may be between about 1 inch andabout 50 inches in diameter. In some specific embodiments, module 100may be about 2, about 4, about 8 or about 16 inches in diameter.

FIG. 2 presents a schematic of a single forward osmosis membrane 210unwound or prior to spiral winding. A plurality of such membranes 210may comprise the membranes 110 of FIG. 1. An end cap 250 is positionedat each end of forward osmosis membrane 210. In some non-limitingembodiments, an end cap may be designed in accordance with end cap 350presented in FIG. 3. End cap 350 may include a row of ports 370,separated by spaces 380 in-between. In some embodiments, ports 370 maybe flat tubes. An attachment structure or manifold 360 may facilitatesealing of end cap 350 to the side of membrane 210. The dimensions ofports 370, spaces 380 and manifold 360 may be of any desiredmeasurements and may be separately optimized.

A side view of an end cap 450 is presented in FIG. 4. Manifold 460 maygenerally facilitate attachment of end cap 450 to a membrane pocket. Inoperation, a first fluid may flow through the end cap 450 only throughlumens 475 of the flat tubes 470. A second fluid may flow within space480 around flat tubes 470. FIG. 5 details a cross-section of an end cap550 in which flat tube 570 interfaces with manifold 560. Manifold 560may be sealed to a membrane pocket. An internal portion of manifold 560may be in fluid communication with lumens of tubes 570 and with aninterior region of the membrane pocket, while an external portion ofmanifold 560 may be in fluid communication with space 580 around tubes570 and with an exterior region of the membrane pocket. Thus, first andsecond fluid inlets may be isolated from one another to prevent mixingas illustrated in FIG. 6. FIG. 6 illustrates an end of a spiral woundforward osmosis membrane module 600. Tubes 670 of end cap 650 definelumens 675 and exterior regions 680. A first fluid may enter module 600at first inlet 624 which is in fluid communication with lumens 675. Asecond fluid may enter module 600 at second inlet 626 in fluidcommunication with exterior regions 680. Potting 640 may facilitatefluid isolation of first and second inlets 624, 626. Fluid flow pathsdefined by the interior and exterior regions of the membrane pocket mayalso be fluidly isolated, apart from desired transmembrane transport forosmotic separation as illustrated in FIG. 7. FIG. 7 illustrates amembrane pocket with a first fluid flow path of Solution A along itsexterior region and a second fluid flow path of Solution B along itsinterior region.

In accordance with one or more embodiments, a flat sheet membrane may beused in the production of a spiral wound forward osmosis membranemodule. In some non-limiting embodiments, a flat sheet forward osmosismembrane may be folded upon itself, such as substantially in half. Afirst edge of a membrane sheet may be folded to a second parallel edgeof the membrane sheet. In the case of an asymmetric forward osmosismembrane, the sheet may be folded such that a supporting layer of oneside faces the supporting layer of the other, and the rejecting layer ofeach side faces out. A pocket or compartment may generally be formed outof the folded membrane. In another embodiment, active layers may faceone another in the interior region of the membrane pocket. Otherarrangements of backing and active layers are also possible. A naturallysealed edge of the compartment is formed via the folding operation. Anedge opposite and parallel to the naturally sealed edge may be sealed byany commonly known technique including use of glue, epoxy, adhesive orfriction. The two ends of the folded membrane may also be substantiallysealed, as described below, while providing fluidly isolated inlets andoutlets. In other embodiments, two or more membrane sheets may beattached to form a membrane compartment, rather than folding a singlesheet.

In accordance with one or more embodiments, an end cap may be placed oneach of the two end edges of the folded membrane sheet (the edges whichare normally at either end of a spiral wound housing) in order toachieve separate flow of feed and draw solutions through the module. Thelengthwise sides of the end cap may generally be sealed. The lengthwiseside which will be in the center of the spiral bundle upon rolling maybe optionally affixed to a bar or other internal structural support forthe winding of the sheet. Any known technique may be used to sealinglyattach an end cap to each of the end edges of the folded forward osmosismembrane sheet. One or more turbulence spacers may be included in theinterior of the membrane pocket.

The resulting modified folded forward osmosis membrane sheet, includingend caps, may be wound into a spiral. At this point, the wound membranemay have the flat tubes from the end caps protruding from either end ofthe wound membrane bundle. These ends may then be potted. In someembodiments, each end may be dipped in an epoxy or other form ofsealant. In one non-limiting embodiment, approximately half of thelength of the tubes may be sealed in this manner. The ends of the epoxysealings may then be cut after potting to allow fluid flow into thelumens of the tubes. In some non-limiting embodiments, approximately aquarter of the length of the tubes may remain sealed.

Each end of the membrane bundle may then be mounted or sealed inside anexterior housing. During operation, feed solution such as brine orseawater may be directed into the space in-between the epoxy block andthe main sheet winding, flowing around the ports into the housing andalong the seawater side of the membrane. Likewise, draw solution may bedirected into the open ends of the ports, flowing into the membranehousing and along the draw solution side of the membrane. Thisconfiguration may allow for similar fluid dynamics on both sides of theosmotic membrane.

A system, such as a desalination or other treatment system, may includea plurality of spirally wound forward osmosis membrane modules. Aplurality of spirally wound forward osmosis membrane modules may bearranged in an array. A system may include a plurality of inlets andoutlets. A source of first and second solutions may be fluidly connectedto the membrane module(s) such as a source of a feed solution and asource of a draw solution. In some embodiments, a separation system,such as a distillation system, may be fluidly connected to an outlet ofthe membrane module. The separation system may treat a dilute drawsolution produced by the forward osmosis process to produce potablewater or other product stream as well as to recover the draw solution.The draw solution may then be recycled back to an inlet of the forwardosmosis membrane module(s) while the product water may be delivered to apoint of use. Distillation columns, such as those described in WIPOPublication No. WO 2007/146094 to McGinnis et al. which is herebyincorporated herein by reference in its entirety for all purposes, maybe implemented in accordance with various embodiments.

In accordance with one or more embodiments, devices, systems and methodsmay generally involve a controller for adjusting or regulating at leastone operating parameter of the device or a component of the system, suchas, but not limited to, actuating valves and pumps, as well as adjustinga property or characteristic of one or more fluid flow streams throughthe spirally wound forward osmosis membrane module. A controller may bein electronic communication with at least one sensor configured todetect at least one operational parameter of the system, such as aconcentration, flow rate, pH level or temperature. The controller may begenerally configured to generate a control signal to adjust one or moreoperational parameters in response to a signal generated by a sensor.For example, the controller can be configured to receive arepresentation of a condition, property, or state of any stream,component or subsystem of a forward osmosis separation device. Thecontroller typically includes an algorithm that facilitates generationof at least one output signal which is typically based on one or more ofany of the representation and a target or desired value such as a setpoint. In accordance with one or more particular aspects, the controllercan be configured to receive a representation of any measured propertyof any stream, and generate a control, drive or output signal to any ofthe system components, to reduce any deviation of the measured propertyfrom a target value.

Having now described some illustrative embodiments of the invention, itshould be apparent to those skilled in the art that the foregoing ismerely illustrative and not limiting, having been presented by way ofexample only. Numerous modifications and other embodiments are withinthe scope of one of ordinary skill in the art and are contemplated asfalling within the scope of the invention. In particular, although manyof the examples presented herein involve specific combinations of methodacts or system elements, it should be understood that those acts andthose elements may be combined in other ways to accomplish the sameobjectives.

It is to be appreciated that embodiments of the devices, systems andmethods discussed herein are not limited in application to the detailsof construction and the arrangement of components set forth in thefollowing description or illustrated in the accompanying drawings. Thedevices, systems and methods are capable of implementation in otherembodiments and of being practiced or of being carried out in variousways. Examples of specific implementations are provided herein forillustrative purposes only and are not intended to be limiting. Inparticular, acts, elements and features discussed in connection with anyone or more embodiments are not intended to be excluded from a similarrole in any other embodiments.

Those skilled in the art should appreciate that the parameters andconfigurations described herein are exemplary and that actual parametersand/or configurations will depend on the specific application in whichthe systems and techniques of the invention are used. Those skilled inthe art should also recognize or be able to ascertain, using no morethan routine experimentation, equivalents to the specific embodiments ofthe invention. It is therefore to be understood that the embodimentsdescribed herein are presented by way of example only and that, withinthe scope of the appended claims and equivalents thereto; the inventionmay be practiced otherwise than as specifically described.

Moreover, it should also be appreciated that the invention is directedto each feature, system, subsystem, or technique described herein andany combination of two or more features, systems, subsystems, ortechniques described herein and any combination of two or more features,systems, subsystems, and/or methods, if such features, systems,subsystems, and techniques are not mutually inconsistent, is consideredto be within the scope of the invention as embodied in the claims.Further, acts, elements, and features discussed only in connection withone embodiment are not intended to be excluded from a similar role inother embodiments.

The phraseology and terminology used herein is for the purpose ofdescription and should not be regarded as limiting. As used herein, theterm “plurality” refers to two or more items or components. The terms“comprising,” “including,” “carrying,” “having,” “containing,” and“involving,” whether in the written description or the claims and thelike, are open-ended terms, i.e., to mean “including but not limitedto.” Thus, the use of such terms is meant to encompass the items listedthereafter, and equivalents thereof, as well as additional items. Onlythe transitional phrases “consisting of” and “consisting essentiallyof,” are closed or semi-closed transitional phrases, respectively, withrespect to the claims. Use of ordinal terms such as “first,” “second,”“third,” and the like in the claims to modify a claim element does notby itself connote any priority, precedence, or order of one claimelement over another or the temporal order in which acts of a method areperformed, but are used merely as labels to distinguish one claimelement having a certain name from another element having a same name(but for use of the ordinal term) to distinguish the claim elements.

1-35. (canceled)
 36. A spiral wound forward osmosis membrane module,comprising: a spirally wound forward osmosis membrane having a firstclosed side and an opposite second closed side defining a membranepocket having an interior region, an exterior region, a first open end,and a second open end; a first end cap sealingly coupled to the firstopen end and comprising at least one first inlet and a manifold havingan interior portion in fluid communication with the at least one firstinlet and the interior region of the membrane pocket and an exteriorportion defining at least one second inlet in fluid communication withthe exterior region of the membrane pocket; and a second end capsealingly coupled to the second open end and comprising at least onefirst outlet and a manifold having an interior portion in fluidcommunication with the at least one first outlet and the interior regionof the membrane pocket and an exterior portion defining at least onesecond outlet in fluid communication with the exterior region of themembrane pocket.
 37. The module of claim 36, wherein at least one of thefirst end cap and the second end cap is coupled to the membrane via anadhesive.
 38. The module of claim 36, further comprising: a housingconfigured for receiving the spiral wound forward osmosis membranemodule; a distributor chamber disposed at one end of the housing andcomprising a first inlet in fluid communication with the at least oneinlet of the first end cap and a second inlet in fluid communicationwith the at least one second inlet of the first end cap; and a collectorchamber disposed at a second end of the housing and comprising a firstoutlet in fluid communication with the at least one first outlet of thesecond end cap and a second outlet in fluid communication with the atleast one second outlet of the second end cap.
 39. The module of claim36, further comprising: a second spirally wound forward osmosis membranehaving a first closed side and an opposite second closed side defining asecond membrane pocket having an interior region, an exterior region, afirst open end, and a second open end; a first end cap sealingly coupledto the first open end of the second spirally wound forward osmosismembrane and comprising at least one first inlet and a manifold havingan interior portion in fluid communication with the at least one firstinlet and the interior region of the second membrane pocket and anexterior portion defining at least one second inlet in fluidcommunication with the exterior region of the second membrane pocket;and a second end cap sealingly coupled to the second open end of thesecond spirally wound forward osmosis membrane and comprising at leastone first outlet and a manifold having an interior portion in fluidcommunication with the at least one first outlet and the interior regionof the second membrane pocket and an exterior portion defining at leastone second outlet in fluid communication with the exterior region of thesecond membrane pocket.
 40. The module of claim 39, further comprising:a housing configured for receiving the spiral wound forward osmosismembrane module; a distributor chamber disposed at one end of thehousing and comprising a first inlet in fluid communication with the atleast one first inlets of the first end caps and a second inlet in fluidcommunication with the at least one second inlets of the first end caps;and a collector chamber disposed at a second end of the housing andcomprising a first outlet in fluid communication with the at least onefirst outlets of the second end caps and a second outlet in fluidcommunication with the at least one second outlets of the second endcaps.
 41. The module of claim 36, wherein at least a portion of one ofthe first and second end caps of the spirally wound forward osmosismembrane is potted.
 42. The module of claim 36, further comprising atleast one spacer positioned along a fluid flow path defined by theinterior region of the membrane pocket from the at least one first inletto the at least one first outlet.
 43. The module of claim 36, whereinthe exterior region of the membrane pocket is defined by a rejectinglayer of the spirally wound forward osmosis membrane.
 44. A watertreatment system, comprising: a spiral wound forward osmosis membranemodule, comprising: a spirally wound forward osmosis membrane having afirst closed side and an opposite second closed side defining a membranepocket having an interior region, an exterior region, a first open end,and a second open end; a first end cap coupled to the first open end andcomprising at least one first inlet in fluid communication with theinterior region of the membrane pocket and at least one second inlet influid communication with the exterior region of the membrane pocket; anda second end cap coupled to the second open end and comprising at leastone first outlet in fluid communication with the interior region of themembrane pocket and at least one second outlet in fluid communicationwith the exterior region of the membrane pocket, wherein the membranemodule is constructed and arranged to define isolated and substantiallyparallel first and second fluid flow paths between the first end cap andthe second end cap along a longitudinal axis of the module and the atleast one first inlet and the at least one first outlet are fluidlyconnected to the first fluid flow path; and the at least one secondinlet and the at least one second outlet are fluidly connected to thesecond fluid flow path.
 45. The system of claim 44, further comprising asource of a first solution fluidly connected to the first inlet, and asource of a second solution fluidly connected to the second inlet. 46.The system of claim 45, wherein the source of the first solution is asource of a saline solution.
 47. The system of claim 45, wherein thesource of the second solution comprises a source of a draw solution. 48.The system of claim 47, wherein the draw solution comprises ammonia andcarbon dioxide in a molar ratio of greater than 1 to
 1. 49. The systemof claim 44 further comprising a control system configured to control atleast one of a flow rate of the first solution at the first inlet and aflow rate of the second solution at the second inlet.
 50. The system ofclaim 44, further comprising a separation system fluidly connected toone of the first and second outlets.
 51. The system of claim 50, whereinan outlet of the separation system is fluidly connected to one of thefirst and second inlets.
 52. A method of facilitating a water treatmentprocess, comprising: providing a spiral wound forward osmosis membranemodule, the module comprising: a spirally wound forward osmosis membranehaving a first closed side and an opposite second closed side defining amembrane pocket having an interior region, an exterior region, a firstopen end, and a second open end; a first end cap sealingly coupled tothe first open end and comprising at least one first inlet and amanifold having an interior portion in fluid communication with the atleast one first inlet and the interior region of the membrane pocket andan exterior portion defining at least one second inlet in fluidcommunication with the exterior region of the membrane pocket; and asecond end cap sealingly coupled to the second open end and comprisingat least one first outlet and a manifold having an interior portion influid communication with the at least one first outlet and the interiorregion of the membrane pocket and an exterior portion defining at leastone second outlet in fluid communication with the exterior region of themembrane pocket; fluidly connecting a source of a draw solution to theat least one first inlet; and fluidly connecting a source of an aqueoussolution to be treated to the at least one second inlet.
 53. The methodof claim 52, wherein fluidly connecting a source of a draw solution tothe first inlet comprises fluidly connecting a source of a draw solutioncomprising ammonia and carbon dioxide in a molar ratio of greater than 1to
 1. 54. The method of claim 52, further comprising fluidly connectingthe first outlet to a distillation column.
 55. The method of claim 54,further comprising fluidly connecting an outlet of the distillationcolumn to the first inlet.